NUTRITION

A proper diet requires a balance of carbohydrates, fats, and proteins. In addition the body requires many phytochemicals, vitamins, minerals, enzymes, and water.

Food Intake Food energy measured in Calories Carbohydrates -

obtained primarily through plants Monosaccharides used for cellular

fuel Minimum carbohydrates = 100

g/day

Lipids < 30% of calories Mostly triglycerides Saturated fats usually from animals Cholesterol only from animals Neutral fats provide insulation and

energy reserves Phospholipids for membranes and myelin Cholesterol for membranes, vitamin D,

steroid hormones, and bile salts

Proteins = 0.8 g/kg of body wt

8 Essential amino acids Plants usually lack 1 or more essential

amino acids / Animal protein usually contains all

Amino acids used to build structural proteins and enzymes

VITAMINS: "vita" = Latin word for life.

Vitamins are organic substances that act as coenzymes, chemicals that assist the enzymes in the bodies reactions. They do not provide energy or calories.

Vitamins may be either Fat Soluble or Water Soluble.

Fat soluble vitamins

are stored in the body's fatty tissues. Fat soluble vitamins include the vitamins A D E K.

Vitamin A

Found in fish, liver, eggs, butter, yellow & green vegetables, fruits

Needed for healthy skin, eyes, bones, teeth.

Deficiency causes night blindness, skin disorders, kidney stones

Vitamin D

Found in liver, fish, eggs, milk, sunlight

Needed for growth, healthy bones, metabolism of calcium & phosphorus

Deficiency causes rickets, poor teeth and bones.

Vitamin E

Found in whole grains, leafy vegetables, milk, butter, vegetable oils

Needed for healthy cell membranes, red blood cells

Deficiency causes red cell rupture, muscle disorders

Vitamin K

Found in leafy vegetables, soybeans, made by intestinal bacteria

Needed for normal blood clotting Deficiency causes slow clotting,

hemorrhaging.

Water soluble vitamins

can be dissolved in water but cannot be stored in the tissues.

They must be obtained each day from food.

Water soluble vitamins include

B1 (Thiamine)

B2 (Riboflavin) Niacin B6 (Pyridoxine) Pantothenic

Acid

Biotin B12 Folic Acid C (Ascorbic acid)

Vitamin B1 (Thiamine)

Found in organ meats, whole grains, vegetables

Needed for proper functioning of heart, nervous system, digestion

Deficiency causes beriberi, cardiovascular disorders.

Vitamin B2 (Riboflavin) Found in liver, poultry, milk, eggs, cheese,

fish, green vegetables, whole grain Needed for metabolism of protein,

carbohydrates, and fats, healthy skin Used to make FAD for metabolism Deficiency causes dim vision, premature

aging, sore mouth

Vitamin B6 (Pyridoxine)

Found in meats, liver, whole grains, vegetables

Needed for sodium and phosphorus balance

Deficiency causes anemia, nausea, loss of appetite, nervousness

Vitamin B12

Found in Liver, meats, eggs, cheese, dairy products

Needed for red cell production, healthy nervous system.

Deficiency causes pernicious anemia.

Vitamin C

Found in citrus and other fruits, leafy vegetables, tomatoes, potatoes

Needed for healthy blood vessels, resistance to infection, healing

Deficiency causes scurvy, bruising, bleeding gums

Niacin

Found in red meats, organ meats, fish, green vegetables

Needed for metabolism, digestion, nerves, skin

Used to make NAD for metabolism Deficiency causes pellagra, sore

mouth, diarrhea, depression

Folic Acid

Found in green vegetables, liver, whole grains, legumes

Needed for manufacture of proteins and red blood cells, needed for cell division, helps prevent spina bifida

Deficiency causes inflamed tongue, diarrhea, B12 deficiency.

MINERALS:

Inorganic substances that are used in the chemical reactions of the body.

Major minerals needed include: Calcium, Iodine, Iron, Magnesium,

Phosphorus, Potassium, and Sodium. 

Calcium

Found in milk, cheese, vegetables

Needed for strong bones and teeth, blood clotting

Iodine

Found in seafoods, iodized salt

Needed for normal thyroid metabolism, prevents goiter

Iron

Found in liver, meat, eggs Needed for red cell production,

prevents anemia

Magnesium

Found in milk, meat, whole grains, legumes

Needed for proper nerve and muscle functioning

Phosphorus

Found in milk, whole grains, meats, nuts, legumes

Needed for tooth and bone development, ATP, nucleic acids

Potassium

Found in whole grains, fruits, legumes, meat

Needed for proper nerve and muscle function

Sodium

Found in seafood, table salt Needed for water balance,

proper nerve and muscle function

Free Radicals

charged molecules that become oxidized by combining with oxygen or the removal of hydrogen, causing electron deficiency.

seek to regain the electron by removing it from other molecules, thus oxidizing them.

set up a chain reaction that may damage cell structures such as DNA, cell membranes, or needed enzymes.

Free radicals may be produced by normal metabolic processes, the immune system in response to disease, exposure to chemicals, toxins, or radiation. Free radical generation may be increased by exercise and stress.

Damage caused by free radical generation is a major cause of the degenerative effects of aging, may cause cancers, damage to arterial walls leading to heart disease and/or stroke, and lead to other degenerative diseases such as Alzheimer’s.

Antioxidants

have a protective effect by neutralizing free radicals.

best known antioxidants are Vitamin C, Vitamin E, and beta carotene.

many others and possibly many yet to be discovered.

proper number, types, and balance of is an important part of nutrition.

METABOLISM

Sum of all the chemical reactions occurring within

the body

Types of Metabolic Reactions

Anabolic reactions - energy requiring synthesis reactions

Catabolic reactions - energy releasing reactions that generate ATP

Enzymes - globular proteins that act as catalysts

Increase reaction rates Holoenzyme - a two-part enzyme

consisting of a protein part and an organic cofactor Apoenzyme - the protein portion Coenzyme - the organic cofactor;

usually a vitamin

Energy Production Oxidation reactions - loss of an

electron by an atom or molecule Reduction reactions - involves the

gain of electrons by a molecule Coupled redox reactions

Cellular Respiration

Oxidation of Glucose

Glucose Metabolism Glycolysis Acetyl Coenzyme A Krebs Cycle Electron Transport Chain

Glycolysis Glucose molecules are broken down

into two molecules of pyruvic acid in the cytoplasm of the cell

Net gain of 2 molecules of ATP No oxygen required Fate of pyruvic acid depends on the

oxygen availability

Glycolysis Glucose C6H12O6

Glucose-6-phosphate ATP Fructose-6-phosphate ADP ATP Fructose 1,6, diphosphate ADP Glyceraldehyde-3-Phosphate or

Dihydroxyacetone Phosphate 2Pyruvate (pyruvic acid) + 2NAD + 4ATP 2C3H4O3 + 2NADH+ + 2ATP (net)

Acetyl CoA Formation

Pyruvic acid is decarboxylated by the removal of CO2 into a two carbon acetyl group

Occurs in the mitochondria of the cell

Krebs Cycle - TCA Cycle Formation of citric acid

when oxaloacetic acid combines with acetyl CoA

Organic molecules are broken down, carbon dioxide is released and hydrogen atoms are removed & transferred by coenzymes NAD & FAD

Kreb’s Cycle Acetyl CoA + Oxalocetic Acid Citric Acid Isocitric Acid CO2 NADH2

alpha-Ketoglutaric Acid CO2 NADH2

Succinyl CoA ATP Succinnic Acid FADH2

Fumaric Acid Malic Acid NADH2

Electron Transport Involves electron carrier molecules

that will release energy in a controlled way

This energy is used to generate ATP Occurs inner mitochondrial

membrane Chemiosmosis

Glucose Anabolism Glycogenesis - conversion of glucose

to glycogen; stimulated by insulin Glycogenolysis - hydrolysis of

glycogen to form glucose; stimulated by glucagon

Gluconeogenesis - synthesis of glucose from non-carbohydrates such as fats and amino acids

Lipid Metabolism

Lipid Catabolism - Lipolysis

Hydrolysis of triglycerides into glycerol and fatty acids

Glycerol converted to G 3-P and then into pyruvic acid, then into the Kreb’s cycle

Beta -oxidation of fatty acids occurs forming two-carbon fragments which is then attached to coenzyme A, forming acetyl CoA

Protein Metabolism Proteins are converted into substances

than can enter the Kreb’s cycle by deamination - loss of (NH2) from amino

group decarboxylation - loss of CO2 molecule dehydrogenation - loss of hydrogen

atom Protein synthesis involves transcription

and translation